Ultrafast ablation dynamics in fused silica with a white light beam probe

Ping Han Wu*, Xuan Yu Yu, Chung-Wei Cheng, Che Hao Liao, Shih Wei Feng, Hsiang Chen Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

This study demonstrates a non-degenerate pump-probe spectroscopy with a white light beam probe based on a regenerative, amplified, mode-locked, Ti:sapphire laser. This white light beam probe is produced by supercontinuum generation of sapphire crystal after ultra-short pulse excitation. To implement the pump-probe experimental operation, the ablation dynamics with and without fresh spot measurements in fused silica samples are demonstrated. Combining the time-resolved differential reflection profiles in the white light range and X-ray photoelectron spectroscopy spectra of fused silica, the following ablation dynamics processes can be observed: Without fresh spot measurements, once carriers are excited, first, the three absorption bands of the intrinsic defect sites are observed within 750 fs. Then, a fast recovery is observed. This recovery comes from defect-trapped carriers excited to conduction bands through hot-carrier-phonon interactions. In the final step, a rapidly rising signal is observed after 800 fs. This signal rise comes from the creation of freeelectron plasma, the density of which increases with increasing excitation energy accumulation. With fresh spot measurements, time delay of carrier dynamics among the three bands can be identified clearly within 750 fs. The intrinsic defect sites of fused silica play the key role during the ultrafast laser ablation process.

Original languageEnglish
Pages (from-to)16390-16400
Number of pages11
JournalOptics Express
Volume19
Issue number17
DOIs
StatePublished - 15 Aug 2011

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